β-tricalcium phosphate as a bone substitute for dorsal spinal fusion in adolescent idiopathic scoliosis:: preliminary results of a prospective clinical study

The aim of this study is to evaluate the ability of beta -tricalcium phosphate (TCP) in granular form to achieve dorsal spondylodesis in adolescent idiopathic scoliosis (AIS). Twenty-eight patients underwent surgical correction and were followed up for 13 +/- 8 (range 6-33) months. Posterolateral grafting was performed, using either autograft bone mixed with allograft bone (n=19; "bone group") or autograft bone mixed with 25 g TCP (n=9; "TCP group"). Patients were followed by clinical examination, X-rays and computed tomographic (CT) scans to measure bone mineral density. Fusion involved 12 +/- 1 (range 10-14) vertebrae. The segments were fused after 6 +/- 1 months in both groups according to the radiographs. No pseudarthrosis was observed. Bone mineral density was 430 +/- 111 (range 273-629) mg/cm(3) in the TCP group versus 337 +/- 134 (range 130-669) mg/cm(3) in the bone group. Resorption of TCP was complete on the radiographs after 8 +/- 2 (range 6-10) months. Based upon the results of this small preliminary study, the use of TCP appears to be a valuable alternative to allografts for application in the spine, even when large amounts of bone are needed.